Depends, the early A7-8 had them to play a little higher up to blend well with the 811 horn/800 Hz XO and the A5, A7-500 cab didn't have them for the blending to the 511 and larger horns with 500 Hz XOs. I guess at some point the 'bean counters' forced them to standardize on the one that they made the most of, making these early cabs a minor collector item:
http://www.lansingheritage.org/images/altec/plans/1960's-lf-design/page04.jpg
GM
If you guys are talking about the baffle not being cut right to the flare then I understand. I think the word lip threw me off. It looks like it was cut at maybe 7 or 7.5 inches instead of the stock 8"? Is that what you mean?
All this time I am thinking about the lip at the mouth where the moulding is mounted.
I confirm that in my case, the baffle opening is 8 inches (203 mm). The horn is a little wider that on some drawings. The recess is about 8 mm.
Thank you very much
You're welcome!
This is where the horn unloads and transitions to bass reflex. It can be made more gradual by installing baffle 'wings' same as originally used (though it needs to be setting on the floor for max flatness). Ideally, the top baffles would be used also except with a gasketed cutout for the horn: http://www.lansingheritage.org/images/altec/specs/pro-systems/800/page2.jpg
If tuned as original and driven with a matching impedance amp it will be ~flat down to 70 Hz in 2pi (half) space, so as you can see, with some room/boundary gain and a little EQ it can be made ~flat down far enough to handle anything on vinyl and most tapes with near 'live' dynamics.
The 'recess' in response I referred to would be higher up in the ~500-700 Hz BW where the 811 horn's smaller size can't quite 'bridge the gap' to the mid-bass horn's roll off without increasing its HF response with a smaller low pass filter (driver cutout area).
GM
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Well sent out my other 416 8A yesterday on its way to Bill for a recone!, then I will have both again in my cabs! Can't til I get it back!
How much more does putting wings on the A7 help the bass? Just curious my EQ is flat all the way to 160 I think then it dips under from there so my bass is great now just wondering. Also what insulation is best for these cabs? I took my foam out for now and it sounds great with nothing in them!
How much more does putting wings on the A7 help the bass? Just curious my EQ is flat all the way to 160 I think then it dips under from there so my bass is great now just wondering. Also what insulation is best for these cabs? I took my foam out for now and it sounds great with nothing in them!
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Good question. Sorry I don't have measurements. From memory, it just tends to fill things out a bit and help dynamics - more of a midbass thing. They were better with than without, but the difference was not huge.
I need to try it with mine.
Don't they already have mid bass from the horn loaded part? I have been thinking of trying mine like GM showed in that link, with wings on top and both sides too..
Hi all,
I have followed GM recommendation and built wings for my 825. I will keep them! They do not significantly extend the bass, but improve linearity around 160 Hz, and I can hear it...
I have also add more fiberglass since I found in an article written by Jean Hiraga recommending to do it for this cabinet. The improvement with the measurement is spectacular! I am not at home today and I cannot post the resulting FR. I will do it when I am back home.
Thanks again to GM
I have followed GM recommendation and built wings for my 825. I will keep them! They do not significantly extend the bass, but improve linearity around 160 Hz, and I can hear it...
I have also add more fiberglass since I found in an article written by Jean Hiraga recommending to do it for this cabinet. The improvement with the measurement is spectacular! I am not at home today and I cannot post the resulting FR. I will do it when I am back home.
Thanks again to GM
under my stairs, I have a pair of UREI 813As, featuring the ceramic version of the Altec 604. (8H?) The drivers are stored away, along with the bottom Eminence 15" woofers. This is the most er, DYNAMIC speaker I've ever heard but suffers in several areas.
1) For the speakers to sound their best, they have to be played loud. And I mean LOUD. They somehow open up when they really start pushing out the decibels. This makes them less-than-popular with the other members of my household.
2) 'Soundstaging" doesn't stack up compared to planars - the big cabinet face certainly doesn't help.
3) they are a bit forward and with the wrong source material - watch out!
Someday I would like to build a more narrow cabinet with the same liter size and redo the time-aligned crossover... but first I need a bigger house!
On a related note, I've also heard the no-letter UREI 813 with the Alnico Altec 604s and it does sound better to my ears.
1) For the speakers to sound their best, they have to be played loud. And I mean LOUD. They somehow open up when they really start pushing out the decibels. This makes them less-than-popular with the other members of my household.
2) 'Soundstaging" doesn't stack up compared to planars - the big cabinet face certainly doesn't help.
3) they are a bit forward and with the wrong source material - watch out!
Someday I would like to build a more narrow cabinet with the same liter size and redo the time-aligned crossover... but first I need a bigger house!
On a related note, I've also heard the no-letter UREI 813 with the Alnico Altec 604s and it does sound better to my ears.
